#include<sys/eventfd.h>
#include<iostream>
using namespace std;
int main()
{
    eventfd_t rsu;
    int efd=eventfd(0,EFD_NONBLOCK);
    eventfd_write(efd,1);
    eventfd_write(efd,1);
    eventfd_write(efd,1);
    eventfd_read(efd,&rsu);
    std::cout<<rsu;

    
   
    
}